Machine for making pressed articles



July 23, 1940. F. SCHNELL MACHINE FOR MAKING PRESSED ARTICLES July 23, 1940.l F. SCHNELL MACHINE FOR MAKING PRESSED ARTICLES Filed Aug. 17, 1937 2 Sheets-Sheet? Patented July 23, 1940 UNITED STATES PATENT OFFICE 2,209,141 MACHINE FOR. MAKING PRESSED ARTICLES Fritz Schnell, Chemnitz, Germany Application August 17, 1937, Serial No. 159,551

.. In Germany August 18, 1936 1 Claim.

This invention -relates to a press for making articles of synthetic material which are pressed to the desired shape and require high pressure, as for example, artificial resin pressings made from a laminated material consisting of layers of paper or fabric impregnated with artificial resin. After the pressing operation the pressings must be cooled, while the high pressure. is maintained, and this requires approximately the same time as the pressing. The presses, which are usually constructed as hydraulic presses, are not fully utilised, so that a poor return is obtained for the high installation costs.

The invention provides a press more particuv larly for making artificial resin pressings which require high pressure and are arranged one above another in the same place and the novelty consists in this, that in addition to the ordinary die and plunger, intermediate dies, which can be used as intermediate plungers, are provided which can be moved in the vertical direction with l the main plunger, and preferably can be driven thereby. The advantage is that the pressing period can be shortened in accordance with the number of dies used, so that for example, when using two dies and two plungers in the same time, approximately twice as many pressings can be made as with the ordinary arrangements.

Two different methods are possible. Firstly the pressing of the individual parts and the subsequent cooling of the parts can be effected simultaneously, that is all the pressings are pressed with one stroke of the press and they cool together while the press is closed. Alternatively, it is possible to effect the pressing of the parts successively, that is, with two strokes of the press, and the cooling of the parts accordingly takes place successively. The advantage of this second method is that a smaller stroke of the press can be used and also that during the cooling of one pressing the workers are available for operating the free die.

The intermediate dies and plungers provided according to the invention may be guided on the same guiding rods as the main die and plunger. According to the invention preferably in each case an intermediate die is made integral with an intermediate plunger. In this way each in* termediate die and plunger is of small height, so that the operation of such an intermediate die is considerably simplified.

A further useful feature of the invention is that the main die or the main plunger, or preferably the intermediate die, is provided with a locking device which can be attached to the adjoining parts. The advantage of this is thatl in the method in which the pressing and cooling op eration takes place successively, the pressure during the cooling can be replaced by this locking device. For this purpose the locking device is preferably mounted on an eccentric shaft, by means of which it is given the necessary tension.

According to the invention the intermediate die is tted with connections and pipe conduits for introducing cooling air or other medium.l This provides the same good cooling possibility forI the intermediate die as for the main die. l

The drawings illustrate the device for carrying out the method in a constructional example.

Fig. 1 shows the head and foot of a hydraulic press with main die, main plunger and intermediate die.

Fig. 2 is a side elevation of the arrangement.

According to Fig. 1 an ordinary hydraulic press has a head I and a foot 2. On the head I' is arranged a plunger 3 with plunger head 4, the head 4 being constructed in the shape of the pressing to be made. On the foot 2 of the press is provided a die 5, the moulding part 6 of which also has the same shape as the pressing. Guiding rods 'I and 8 form the usual guides for the downwardly moving plunger and on these rods I and 8 an intermediate die 9 is guided on I0. The intermediate die 9 is fitted at its lower part with an intermediate plunger II which ts the lower die 6 and carries above a die I2 which is constructed correspondingly to the upper plunger 4. On the intermediate die 9, lateral locking devices in the form of stirrups I3 are mounted on trunnions I4 of an eccentric shaft I6 and on trunnions I5 of the main die 5. The eccentric shaft IS carrying the trunnions I4 is moved by means of a lever I'I which can be actuated by a, device provided for the purpose or can be actuated by the machine itself, for example by means of an ordinary hydraulic arrangement. A catch I8 holds the lever I1 and with it the trunnions |`4 in the tensioned position. 'I'he main plunger 3, like the main die 5, is provided with trunnions I9 to which the stirrups I3 can be attached, in which case the lever I1 for stressing the eccentric in Fig. 1 is turned to the left through and the catch I8 is xed in the bolt hole 2li. The intermediate die, like the main die 5 and the main plunger 3, is provided with connections 2| for introducing a cooling medium, for example compressed air.

The pressing operation is carried out as foly lows with the machine illustrated:

When simultaneously pressing two articles steel bushes made from laminated articial resin material, the intermediate die is brought into a middle position in such a mannerl that both' dies 6 and I2 can be charged with material. After the lling the intermediate die is ylowered on to the main die and, by means of the main plunger 3, both parts are simultaneously pressed with the pressure of 300 to 400 kilograms per square centi- .meten which is required for articial resin laminated material, the'pressure used being determined according to'the properties of the material. After the pressure indicator has lcome to rest at the desired value, Ycalculated for example at 350 kilograms persquare centimeter and the pressure has been maintained for a time according to the material' being used, the pressings'are cooled while maintaining the pressure by compressed air or other cooling agent being admitted throughv the connections 2|. v n

In successive pressing and cooling, for example, the lowerl die is charged with material and the article is pressed oy means of the plunger Il provided on the intermediate die 9, the stirrups I3 beirigconnected with the main die 'When the material yields' no furtherthe stirrups I3 are After this the arti-v tachment of the locking devices I 3, the lower pressing is cooled. After the cooling of the lower pressing the locking device 'is again attached to the main plunger 3 and the lower die is emptied,

after which the operation is repeated.

At the rst charging of the upper or of the lower die when pressing on thev empty die a spacing ring 22, shown in the iigures in broken lines, is preferably inserted in order to avoid damage to the surfaces of the die and plunger.

'Ihe new method is suitable for all pressed materals in which the pressing is cooled under` pressureafter being pressed at the highest temperature. It is also suitable for artificial resin pressed materials which require high pressure at thehighest temperature, as for example, all artificial resin materials which are reinforced with materials'and the like.

What I claim is: .f ln a press, a main die, guideposts extending upwardly from said die, a main plunger movable laminated material such as paper, fabric, fibrous on saidguide posts, an intermediate die and plunger movable on said guide posts, a trunnion on said main'die, a trunnion carried by said main plunger, a shaft `rotatably mounted on the inter-` mediate die, a trunnion carried by the shaft vec' centrically arranged with respect to the aXisof saidlshaft, a stirrup swingably arranged on the trunnion of said shaft adapted toengage thetrunnion of the main die or Vthe trunnion of the main plunger, and a lever for rotating said shaft. l l ,FRITZ SCHNELL. 

